Steering columns have diverse functions in motor vehicles. They firstly serve for fastening the steering wheel and for mounting the steering shaft or steering spindle on the vehicle body. They also serve for fastening add-on parts, such as, for example, an anti-theft means or operator control elements. The steering columns are sometimes also adjustable mechanically or electrically in the axial direction and vertical direction in order to be able to adapt the position of the steering wheel to the requirements of the driver. Finally, steering columns are also intended to yield in a controlled manner in the event of an impact of the vehicle against an obstacle, in order to absorb impact energy of the driver against the steering wheel and thereby to reduce the risk of injury for the driver. Along with all of these requirements, it is also required that steering columns take up little construction space, have a low weight and operate without play and noise.
One possibility of designing steering columns to be reasonably priced and lightweight consists in the use of extruded profiles. In comparison to die-cast components, extruded profiles have the advantage of low production costs.
Steering columns in which extruded profiles are used are therefore already known from the prior art.
The document U.S. Pat. No. 8,863,609 B2 discloses, for example, a steering column in which the casing unit, in more precise terms the outer casing tube, is manufactured from an extruded profile. This steering column has the particular characteristic that the tensioning pin for releasing and blocking the adjustment acts on one side on the outer casing tube and does not continue to the other side of the casing tube.
The document FR 3004154 presents a casing unit for a steering column, wherein the casing unit is produced from an extruded profile. The various functional portions required are, for example, fastening regions, guides for the adjustment function, bearing seats and gripping points for additional components.
This document also clearly shows that the bearing for the pivot axis of the vertical adjustment and an approximately helical slotted arrangement as an energy-absorbing “crash structure” are directly incorporated into the outer casing tube. This corresponds to the customary design of adjustable steering columns, and it makes the steering column complicated to produce since dedicated machining operations have to be carried out on the workpiece for said functional elements.